Inflatable curtain type airbags are used in general for the side impact protection of the occupant. The airbag covers in the inflated condition the inside of the side windows and part of the pillars of the occupant compartment. Therefore the airbag has a length of approximately or nearly the distance from the A to C or D-pillar, with several attachment portions.
Because of the length of the airbag, there is a risk that the airbag is mounted in a twisted status at the vehicle. If the airbag is attached in a twisted condition, the airbag will not be properly deployed during a crash, and does not cover the interior side structure of the car as needed in case of a side impact.
Therefore it was already proposed in the JP 2004-224255 to use an indication thread formed by weaving or sewing a thread of a colour different from the base cloth of the airbag body. When the airbag is folded regularly and attached untwisted, the indication thread extends in the longitudinal direction of the airbag body. So far it is possible to indicate a wrong twisted attachment by the indication thread, when it is extending in a shape of a spiral along the airbag.
Nevertheless the use of the indication thread is problematic, because the rather thin indication thread is hardly visible, especially when the operator needs to mount the airbag at the inside of the roof rim from the outside of the vehicle. In such a case it might be that the operator cannot see the indication thread or can only see a part of the indication thread. When the twisted attachment is not detected, the interior trim panel can be mounted afterwards without any problems.